Fixed for python

approved

approved then, thx :)

Done.

Seems fine, but maybe you should transfer the test with big array a from Small random Test Cases section to fixed cases, for consistency

In the random tests, the assertion message always shows the user result as a string, even when it isn't one.

You can use the inspect method:

expect(actual).to eq(expected), "Incorrect answer for input = #{input.inspect}.\nActual: #{actual.inspect}\nExpected: #{expected.inspect}"

Strings are mutable in Ruby.

In the random tests, you can pass a string copy to the user solution, so the input string shown in the assertion message is not affected by user solution.

actual = validation(input.dup)

Custom messages in the sample / fixed tests are hiding the user solutions.

Instead of more useful messages like:

expected: 1
     got: nil

(compared using ==)

The user can only see:

Incorrect answer for input = '  '.

So solvers will have to manually print out their result to debug their code (expected solutions are still visible in the it message)

You can remove the assertion messages in the fixed tests, to display the user result.

Python does not test this case at all

Upgraded the version from 8.1.3 to 18; improved test structure and added lodash instead of Math.random (with Katafix)

resolved for all languages

resolved for all languages (+ resolved the problem with pseudo-random tests as well)

Yeah, it should be, so that would be better fitting to its name.

Made a fix with adding such details to description, seems like to be explained enough.